1. Field of the Invention
The present invention relates to a heat exchanger and, in particular, to a heat exchanger effectively applied to an air conditioner.
More specially, it relates to a heat exchanger and a heat transfer member, for improving the heat-exchanging performance thereof by producing a turbulent air-flow flowing through a heat-exchanging member thereof, which are preferably applied to, for example, a vehicle.
2. Description of the Related Art
In a conventional heat exchanger, fins have slit pieces, which are segments of the fins and are arranged in a staggered manner in the air flow direction, and the upstream sides, in the air flow, of the slit pieces are bent at around 90 degrees to form bend potions. Due to the bend portions, the air flow around the fins is disturbed so that the thickness of the temperature boundary layer around the fins is prevented from increasing in order to increase the heat transfer coefficient between the fins and air (for example, refer to Patent document 1).
Another heat exchanger has a plurality of pin-shaped (needle-shaped) fins arranged in an air flow and, thereby, the heat exchanging ability of the heat exchanger is improved.
[Patent Document 1]
Japanese Unexamined Patent Publication (Kokai) No. 63-83591
In the invention disclosed in Patent document 1, slit pieces are formed by cutting and raising parts of a thin plate-shaped fin and bend portion are formed by bending upward the front ends (font edges) of the slit pieces, at around 90 degrees. In this configuration, the above-mentioned bend portions have disadvantages, in the manufacturing thereof, as described below.
That is, as in the invention disclosed in Patent document 1, all bend portions are formed by bending the front ends of the slit pieces, the bending force in the same direction is continuously exerted on the thin plate-shaped fin material and, therefore, while the bend portions are formed the fin material is deformed in a state where the repeated deformations of the fin material are accumulated in the same direction, in other words, the fin material is bent in a transverse direction of the fin material, that is, the air flow direction.
The slit pieces should be regularly arranged at a constant pitch but, as described above, in the invention disclosed in Patent document 1 the fin material is likely to be deformed in a state where the repeated deformations of the fin material are accumulated in the same direction, that is, the fin material is bent in a transverse direction of the fin material, that is, the air flow direction. Therefore, it is difficult to reduce the variation of the pitches between the slit pieces. When the variation of the pitches between the slit pieces is increased, the heat transfer coefficient between the fins and air is decreased and, therefore, the desired heat exchanging ability of the fins is unlikely to be obtained.
In a heat exchanger having a plurality of pin-shaped (needles-shaped) fins arranged in the air flow, the weight of the heat exchanger is increased by arranging the fins, that is, a plurality of pins, and the productivity of the fins is deteriorated by arranging a plurality of pins on the heat exchanger. Therefore, it is difficult to realize the mass production thereof.
If a plurality of the pins are formed by cutting the areas between two pins, much material to be scrapped, during cutting, is produced and, therefore, the material is not effectively used. As a result, it is also difficult to realize the mass production thereof.